Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque

h,w=map(int,input().split())
s=[list(input()) for i in range(h)]

cnt=0
for i in s:
    cnt+=i.count('.')

sy,sx=0,0
gy,gx=h-1,w-1

dist=[[-1]*w for i in range(h)]
dist[sy][sx]=0

que=deque()
que.append((sy,sx))

while que:
    y,x=que.popleft()

    if y==gy and x==gx:
        print(cnt-(dist[y][x]+1))
        exit()

    for dy,dx in [[1,0],[-1,0],[0,1],[0,-1]]:
        ny=y+dy
        nx=x+dx
        if 0<=ny<=h-1 and 0<=nx<=w-1 and s[ny][nx]=='.' and dist[ny][nx]==-1:
            que.append((ny,nx))
            dist[ny][nx]=dist[y][x]+1

print(-1)